This invention relates to integrators and more particularly to circuitry in an integrated circuit that controls frequency response characteristics over a wide range of frequencies with adjustable capacitance and controllable transconductance.
Circuit components formed in integrated circuits commonly exhibit wide variations in operating characteristics attributable to variations in the semiconductor processes that form the integrated circuit of such components. By traditional design practices, additional or redundant components may be formed in an integrated circuit during the processing phase, and such additional components may thereafter be connected in or out of a circuit using a laser beam to selectively sever connecting links as required to adjust the operating characteristics of the circuit. Alternatively, signal controllable switches may be incorporated into the design of the integrated circuit to selectively connect additional components in response to externally applied control signals. However, such switches are not ideal in that they incorporate appreciable resistance into a circuit in the conductive state which can be detrimental to high frequency operating characteristics of the integrated circuit.
In accordance with one embodiment of the present invention, additional capacitive components may be selectively switched into circuit configuration in response to external control signals without introducing significant resistance with the capacitive components. In addition, controllable gain elements may be selectively controlled to amplify the effectiveness of capacitive components in the circuit for a wide range of operating frequency characteristics of the circuit as selectively configured.